Year 8 Science · Unit 2 · Lesson 1
Challenge Worksheet
Learning Goals
What if…?
Scenario
Scientists discover a new material on the surface of an asteroid retrieved during the JAXA Hayabusa2 mission. Particle analysis shows the material contains only one type of atom, arranged in an extremely hard, interlocking lattice structure similar to diamond. Some scientists claim it is a new element never seen before on Earth. Others argue it might be a compound that appears uniform under extreme pressure, because pressure can force atoms of different types so close together that conventional analysis is fooled.
Using the definitions of element and compound from this lesson, explain how scientists could determine which claim is correct. What specific evidence would be needed, and what would each possible result tell us about the material?
1. Carbon as graphite and carbon as diamond are both pure elements, yet they look and behave completely differently. Using particle-level ideas, explain how two forms of the same element can have such different properties. What does this tell us about the relationship between atomic arrangement and the properties of a substance?
2. A classmate argues: "If you can break water apart into hydrogen and oxygen by passing electricity through it, that proves water was always just a mixture of hydrogen and oxygen." Evaluate this argument. Is the classmate's reasoning correct? Explain what the decomposition of water actually tells us about its classification, and where the classmate's logic goes wrong.
Wrap Up
In one sentence, what was the main idea of this lesson?